There are two types of Seiko watch sources on eBay - Parallel imported and licensed.
All licensed offical Seiko watch comes with at least a 12 month warranty and a Seiko watch box. Licensed Seiko watch is guaranteed with the watch genuineness and the watches are handled in professionally managed procedures during delivery from factory to destination dealers. You don't have to worry much buying a licensed Seiko watch with international warranty.
Parallel imported Seiko watch, is also coming from the same production factory but not offically managed by any authorized Seiko dealer watch shop. Some people brings the watches from the factory directly to their countries for selling. Most probably, those people will not check every Seiko watches' quality and the delivery is not proceeded with a professional way. No warranty is offered for parallel imported Seiko watch but you always enjoy a much lower watch price in return.
Watch price versus satisfaction. It is up to your choice to choose between licensed Seiko watch or parallel imported Seiko watch.
I hope this guide is useful to those Seiko watch lovers.